Investigations on Microstructure, Tensile Properties and Crystallographic Orientation of SAPH440 CMT Weldments

Abstract

In this research, investigations on microstructure, tensile properties and crystallographic orientation were carried out on SAPH 440 steel welded using cold metal transfer (CMT). Comparisons are made between the variables of weld voltage and weld travel speed. Weldments were free from distortion as characteristic of the low heat input from CMT. An optimal condition with excellent surface quality, low defects and high tensile strength was found to be 12 V and 50 mm/min travel speed conditions. The ferrite phase with a body centered cubic crystal structure is presented in the microstructures. Finally, the larger degree of preferred orientation was detected at the {100} plane. In addition, a low recrystallization resulted in low-angle grain boundaries, and higher residual strain in the microstructures was correlated to the high strength of weld seam.